The exists method checks whether a specified path exists in the JSON object.
exists( pathElements )
| Argument | Description |
|---|---|
pathElements
|
(json_path_string_or_integer) The path to check. Specify one or more path elements, which might be object attribute names (strings) or array indexes (integers). |
(Boolean) Returns true if the path exists, false otherwise.
Consider the following JSON:
{
"product": "IDOL",
"component": "CFS",
"version": { "major": 11, "minor": 3 },
"ports": [
{ "type": "ACI", "number": 7000 },
{ "type": "Service", "number": 17000 }
]
}
If this JSON is represented by an object named myJsonObject, you could use the exists method as follows:
print (myJsonObject:exists("ports",0,"type"))
-- true (LuaJsonArrays are zero-indexed)
print (myJsonObject:exists("ports",2,"type"))
-- false (LuaJsonArrays are zero-indexed, and there is no third value)
print (myJsonObject:exists("version", "major"))
-- true